- 06/14/2014
- 1 Min Read
- By: Bryan McPhail
The Secrets of the BMW 8-Series Handle Revealed
A door handle is just a simple mechanical lever right? Well, back when BMW designed the 8-Series coupe in the late 80’s nothing was simple. There are a variety of features and functions contained within its handle. It just so happens I have a disassembled handle mechanism lying around, so let’s see what they put in there!
Window-drop Microswitch
First off, there is a tiny microswitch - this opens with less than a millimeter of travel on the handle itself. This is responsible for one of the 8’s party tricks - the window drops an inch to welcome you into opening the door with only the slightest pressure on the handle. Unfortunately this tiny switch can become an expensive repair item.
[gallery columns="2" ids="3679,3678"]
Heated lock cylinders
One electrical connector is for the heater element around the lock cylinder - this is designed to stop the lock freezing on a cold day.
Lock Cylinder Removed
Lesser known features
The cylinder barrel itself acts on a special 3-microswitch block. Unlike other cars of the era, the key and tumbler do not physically lock the door. Instead, the microswitches signal a central control unit (called the ZKE) that electronically activates and deactivates the locks, the same unit that controls central locking.
The cylinder barrel is actually a 4-way switch in practice - the regular 45 degree turn controls standard lock and unlock, but there is a lesser known feature if you turn the key to 90 degrees as this instructs the ZKE to automatically roll down all the windows. A 90 degree turn on the passenger side also operates a physical override to the electronic lock - useful if you have a dead battery!
Unfortunately these details can make for very fiddly repairs if something goes wrong. A tip on removing the lock cylinder: It is designed to be removed with the correct key in it. (as a security feature) With the key in, the lock cylinder can be removed, and the key stays in when installing the cylinder into a replacement handle. If for some reason you do not have the key (for example swapping a handle from a parts car) then don’t worry as some gentle chisel and hammer work can still remove the cylinder without damage to either it or the surrounding handle.
About the Author: Bryan McPhail
Bryan is a longtime BMW enthusiast in Florida.
